Architects and interior designers consider lighting to be a critical element of the aesthetic appeal of interior spaces they design. Recessed ceiling lighting fixtures are often an important ingredient in lending such appeal. Clean exterior appearances and precise control over intensity and lighting pattern are crucial elements in good design practices.
A common characteristic of downlight fixtures, whether or not for inclined ceilings, is that the lamp is preferably positioned substantially perpendicular to the floor space in order to impart a uniform lighting pattern. Accordingly, the can or housing of conventional downlight fixtures is constructed to be mounted substantially perpendicular to the floor space, regardless of the angle at which the ceiling is inclined. Consequently, conventional inclined ceiling downlight fixtures (as do downlight fixtures for non-inclined ceilings) employ a circular can or housing which, when intersected by the plane of the inclined ceiling, provides an elliptical opening in the ceiling. Such fixtures are disclosed in U.S. Pat. No. 5,124,901 to Sojka, et al., U.S. Pat. No. 4,729,080 to Fremont, et al., and U.S. Pat. No. 2,859,333 to Burliuk, et al.
Such designs also often aim to accommodate a range of ceiling gradients in order to ensure that the lamp is disposed substantially perpendicular to the floor space. The Sojka patent, for instance, discloses a circular can or housing that is adapted to pivot perpendicular to the gradient of an inclined ceiling. This housing surrounds a circular baffle which may be cut at the appropriate angle corresponding to a given gradient. The Fremont patent discloses a circular fixture housing that is cut at an oblique angle to its longitudinal axis corresponding to a particular ceiling gradient, again to provide an elliptical ceiling opening. The Burliuk patent discloses a fixture housing of circular cross-section that is cut at an angle oblique to its longitudinal axis in order to allow a designer to position the lamp at various angles. A flat circular plate to which the lamp may be attached covers the top of the housing so that the angle at which the lamp is disposed may be varied by rotating the plate relative to the housing.